Loose abrasive bodies and method of abrading a workpiece using the same

ABSTRACT

A method of abrading a surface of a workpiece comprises agitating a vessel containing loose abrasive bodies and the workpiece. At least most of the loose abrasive bodies have a maximum dimension of 0.25 to 3 centimeters. On a respective basis, each loose abrasive body comprises abrasive particles secured to an organic substrate by a binder material. The vessel is agitated with sufficient energy such that at least some of the loose abrasive bodies contact and abrade at least a portion of the surface of the workpiece. A plurality of chopped loose abrasive bodies, wherein, on a respective basis, the chopped loose abrasive bodies each comprise abrasive particles secured to a substrate and have a maximum dimension of 0.25 to 1.5 centimeters is also disclosed.

TECHNICAL FIELD

The present disclosure broadly relates to abrasives and methods ofabrading.

BACKGROUND

Additive manufacturing of metals, polymers, composites and ceramics forboth prototyping and manufacturing has increased in importance in recentyears. Additive manufacturing methods such as, for example. Direct MetalLaser Sintering (DMLS) often produce parts with unacceptable surfaceroughness for the parts' intended function. Most users requirepost-processing techniques to reduce the roughness of the surface of thepart before use. Examples of such post-processing steps includevibratory tumbling and abrasive flow machining. In vibratory tumblingabrasive media are tumbled with a part to smooth its surface.

The manufacture of various abrasive articles (e.g., coated abrasivearticles and nonwoven abrasive articles) can generate substantialamounts of scrap during converting to forms such as, for example,abrasive discs. The scrap is typically disposed of by incineration or ina landfill.

SUMMARY

According to the present disclosure, the present inventors havediscovered that scrap generated in the conversion of various abrasivearticles is either already of a desired size (e.g., in the form of apunch out resulting from a perforating operation) or can be chopped to adesired size range and used as abrasive media for vibratory finishing.Not only does this provide a recycling opportunity for the scrap, but itis also unexpectedly discovered that the recycled abrasive media mayactually perform in a superior fashion as compared to an equivalentamount of loose abrasive particles.

In one aspect the present disclosure provides a method of abrading asurface of a workpiece, the method comprising:

providing a vessel containing:

-   -   loose abrasive bodies, wherein at least most of the loose        abrasive bodies have a maximum dimension of 0.25 to 3        centimeters, and wherein, on a respective basis, each loose        abrasive body comprises abrasive particles secured to an organic        substrate by a binder material; and    -   the workpiece; and

agitating the vessel with sufficient energy such that at least some ofthe loose abrasive bodies contact and abrade at least a portion of thesurface of the workpiece.

In another aspect, the present disclosure provides a plurality ofchopped loose abrasive bodies, wherein, on a respective basis, thechopped loose abrasive bodies each comprise abrasive particles securedto a substrate and have a maximum dimension of 0.25 to 1.5 centimeters.The chopped loose abrasive bodies are useful, for example, forpracticing methods according to the present disclosure.

As used herein:

the verb “chop” means to cut into pieces, for example, by a blow by asharp instrument, slicing, or cutting with scissors, die cutting,perforating, cutting with a laser, characterized by clean cuts, andexplicitly excludes shredding operations that tear or rip;

the adjective “chopped” means cut into pieces, for example, by blows,slicing, perforating, or cutting with a sharp implement or laser,characterized by clean cuts, and explicitly excludes torn or rippedshreds;

the term “loose packed”, means compacted using only agitation andgravity; and

the term “vessel” refers to a hollow or concave container used forholding liquids or other contents.

Features and advantages of the present disclosure will be furtherunderstood upon consideration of the detailed description as well as theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 . is a schematic process diagram of an exemplary method 100according to the present disclosure.

FIG. 2 is a schematic cross-sectional side view of an exemplary coatedabrasive article 200.

FIG. 3 is a schematic cross-sectional side view of an exemplary coatedabrasive article 300.

FIG. 4A is a schematic perspective view of an exemplary nonwovenabrasive article 400.

FIG. 4B is an enlarged view of region 4B in FIG. 4A.

FIG. 5 is a schematic perspective view of an exemplary convoluteabrasive wheel 500.

FIG. 6 is a schematic perspective view of an exemplary unitized abrasivewheel 600.

Repeated use of reference characters in the specification and drawingsis intended to represent the same or analogous features or elements ofthe disclosure. It should be understood that numerous othermodifications and embodiments can be devised by those skilled in theart, which fall within the scope and spirit of the principles of thedisclosure. The figures may not be drawn to scale.

DETAILED DESCRIPTION

Referring now to FIG. 1 , exemplary method 100 of abrading a surface 112of a workpiece 110 comprises the steps of providing a vessel 120containing loose abrasive bodies 130 and at least a portion of theworkpiece 110, and then agitating the vessel 120 with sufficient energysuch that at least some of the loose abrasive bodies 130 contact andabrade at least a portion of the surface 112 of the workpiece 110. Atleast most (and preferably all) of the loose abrasive bodies 130 have amaximum dimension of 0.25 to 3 centimeters; for example as shown inFIGS. 2-6 . Respectively, each loose abrasive body 130 comprisesabrasive particles secured to a substrate by a binder material. In someembodiments, the loose abrasive bodies may be constructed of the same ordifferent materials, although they need not be the same size and/orshape. For example, they may be recycled scrap from a common abrasivearticle.

The vessel may be capable of retaining any volume of material, and maybe partially or completely filled with loose packed abrasive bodies,preferably completely filled if compressible loose packed abrasivebodies are used. In either case, there should be sufficient mobility ofthe loose packed abrasive bodies or the workpiece so that there isrelative motion between the bodies and workpiece during agitation. Insome embodiments, the loose packed abrasive bodies fill at least 10volume percent, at least 20 volume percent, at least 30 volume percent,at least 40 volume percent, or even at least 50 volume percent of themaximum retaining capacity (i.e., excluding overflow) of the vessel. Insome embodiments, including any of those mentioned in the precedingsentence, the loose packed abrasive bodies fill less than 90 volumepercent, less than 80 volume percent, or less than 70 volume percent ofthe maximum retaining capacity of the vessel. Lesser and greater amountsof the loose abrasive bodies may also be used. Typically, the greaterthe mass of each loose abrasive body, the less important the percentagefill of the vessel, although this is not a requirement.

In some embodiments, in addition to the workpiece and loose abrasivebodies, the vessel may further contain additional optional items suchas, for example, loose abrasive particles, if desired. In otherembodiments, the vessel may be free of such additional optional items.

Any suitable means to agitate the vessel and hence also the loose packedabrasive bodies may be used, including, for example, shaking, vibrating,and/or tumbling. Motion of the vessel may comprise linear, arcuate,elliptical, or random oscillations, for example. In some preferredembodiments, the motion comprises linear reciprocating motion. Theprocess of abrading the workpiece may be batch-wise or continuous.

Methods according to the present disclosure may be carried out, forexample, using a vibratory system that includes a vessel. The vessel maybe hermetically sealed or in some embodiments it may have one or moreopenings (e.g., an opening through which the workpiece extends into thevessel). The system may further include an actuator (e.g., a mechanicalactuator) capable of vibrating the vessel. Preferably, a control modulecontrols the actuator such that the vessel vibrates under resonant ornear-resonant conditions (e.g., resonant acoustic conditions) throughoutthe surface modification process. Use of vibrationally resonantconditions ensures high efficiency use of the supplied energy.Commercially available mixing devices capable of accomplishing the aboveare marketed by Resodyn Acoustic Mixers, Butte, Mont. Laboratory-scaledevices include LabRAM I and LabRAM II controlled batch mixers. Largescale devices are marketed under the trade designations OmniRAM. RAMS,and RAM 55. These devices typically operate at resonant vibrationalfrequencies from 20 to <1 kilohertz (kHz), preferably 40 to 100 hertz,more preferably 40 to 80 hertz, and more preferably 55-65 hertz,although this is not a requirement. The vibrating mixers are alsocharacterized by actuator displacements that are on the order of 0.5inch (1.3 cm), that may be accompanied by an acceleration g-force, whereg=9.8 m/s², of at least 20-g. 30-g, 40-g, 50-g, or even at least 60-g,although this is not a requirement. Further details concerning suitableresonant acoustic mixers can be found, for example, in U.S. Pat. No.7,188,993 (Howe et al.) and U.S. Pat. No. 9,808,778 (Farrar et al.).

In practice, the loose abrasive bodies and the workpiece(s) are disposedwithin the vessel. The workpiece may be loose within the vessel or fixedin a given position relative to the vessel (e.g., mounted to a wall ofthe vessel). The latter configuration may be desirable in instanceswhere selective modification of a portion of the workpiece surface isdesired. The latter configuration may also be desirable if the workpiecehas a large mass and/or is delicate, so that collisions between theworkpiece and the vessel walls are prevented. Advantageously, the looseabrasive bodies may ricochet off the sides and top of the vessel duringvibration such that the workpiece is bombarded from all angles.

Mixtures of two or more types, compositions, shapes, and/or sizes ofloose abrasive bodies may be used. Examples of suitable loose abrasivebodies include coated abrasive articles (e.g., having make and sizelayers or a slurry layer), nonwoven abrasive articles (e.g., surfacefinishing abrasive articles including a lofty open fiber web), convoluteabrasive wheels, and unitized abrasive wheels. Such abrasive articlesare well-known in the art.

Referring to FIG. 2 , an exemplary coated abrasive article 200 hasbacking 220 and abrasive layer 230 according to the present disclosure.Abrasive layer 230, in turn, includes abrasive particles 240 secured tomajor surface 270 of backing 220 by make layer 250 and size layer 260.

Referring to FIG. 3 , exemplary coated abrasive article 300 has backing320 and abrasive layer 330. Abrasive layer 330, in turn, includesabrasive particles 340 and binder 345 according to the presentdisclosure.

Further details regarding coated abrasive articles having make and sizelayers and/or structured abrasive article, and methods of theirmanufacture can be found, for example, in U.S. Pat. No. 4,734,104(Broberg); U.S. Pat. No. 4,737,163 (Larkey); U.S. Pat. No. 5,203,884(Buchanan et al.); U.S. Pat. No. 5,152,917 (Pieper et al.); U.S. Pat.No. 5,378,251 (Culler et al.); U.S. Pat. No. 5,436,063 (Follett et al.);U.S. Pat. No. 5,496,386 (Broberg et al.); U.S. Pat. No. 5,609,706(Benedict et al.); U.S. Pat. No. 5,520,711 (Helmin); U.S. Pat. No.5,961,674 (Gagliardi et al.), and U.S. Pat. No. 5,975,988(Christianson).

Referring now to FIGS. 4A and 4B, exemplary nonwoven abrasive article400 comprises a lofty open low-density fibrous web 410 formed ofentangled filaments 410. Abrasive particles 440 are secured to fibrousweb 410 by binder 420.

Convolute abrasive wheels may be made, for example, by winding anonwoven abrasive article 510, as described above, under tension arounda core member 530 (e.g., a tubular or rod-shaped core member) such thatthe nonwoven abrasive article is compressed, then impregnating with acurable binder precursor and curing. A convolute abrasive wheel 500 isshown in FIG. 5 .

Similarly, unitized abrasive wheels can be made, for example, as withconvolute wheels, except that instead of winding the size layerprecursor coated web, it is stacked and compressed prior to curing. Aunitized nonwoven abrasive wheel 600 is shown in FIG. 6 having aplurality of nonwoven abrasive layers 610.

Further details concerning nonwoven abrasive articles, abrasive wheelsand methods for their manufacture may be found, for example, in U.S.Pat. No. 2,958,593 (Hoover et al.). U.S. Pat. No. 5,591,239 (Larson etal.); U.S. Pat. No. 6,017,831 (Beardsley et al.); and in U.S. Pat. Appl.Publ. 2006/0041065 A1 (Barber, Jr.) and 2018-0036866 (Alkas et al.).

The workpiece may be any object, typically fabricated, where abrading ofthe workpiece surface is desired. Examples include camshafts,crankshafts, and turbine blades. Exemplary workpieces include metalcomponents (e.g., which may be sintered metal parts manufactured byrapid prototyping/3-D printing). Examples of workpiece materials includemetal and metal alloys (e.g., aluminum and mild steel), exotic metalalloys, ceramics, glass, wood, wood-like materials, composites, paintedsurfaces, plastics, reinforced plastics, stone, and/or combinationsthereof. The workpiece may be flat or have a shape or contour associatedwith it.

The loose abrasive bodies may be obtained by chopping correspondingabrasive material involved in the manufacturing process such as, forexample, converting manufacturing waste (e.g., weed) or scrap abrasivegoods. While not required for practice of aspects of the presentdisclosure; in some embodiments, it may be desirable to provide theloose abrasive bodies according to a predetermined specific sizedistribution (e.g., monomodal or polymodal) and/or compositionalspecifications (e.g., two different coated abrasive loose bodies or acombination of coated abrasive loose bodies and nonwoven abrasive loosebodies). It may also be desirable to provide the loose abrasive bodiesas random shapes or specified shapes.

Select Embodiments of the Present Disclosure

In a first embodiment, the present disclosure provides a plurality ofchopped loose abrasive bodies, wherein, on a respective basis, thechopped loose abrasive bodies each comprise abrasive particles securedto a substrate and have a maximum dimension of 0.25 to 3 centimeters(cm), preferably 0.3 to 2.6 cm, more preferably 0.5 to 2.5 cm, and morepreferably 0.7 to 2.5 cm.

In a second embodiment, the present disclosure provides a plurality ofchopped loose abrasive bodies according to the first embodiment, whereinthe plurality of chopped loose abrasive bodies has a predetermined sizedistribution, preferably monomodal or polymodal.

In a third embodiment, the present disclosure provides a plurality ofchopped loose abrasive bodies according to the second embodiment,wherein the predetermined size distribution has at least two modes;e.g., bimodal or trimodal.

In a fourth embodiment, the present disclosure provides a plurality ofchopped loose abrasive bodies according to any of the first to thirdembodiments, wherein at least some of the chopped loose abrasive bodiescomprise chopped coated abrasive articles.

In a fifth embodiment, the present disclosure provides a plurality ofchopped loose abrasive bodies according to any of the first to thirdembodiments, wherein at least some of the chopped loose abrasive bodiescomprise chopped lofty open nonwoven abrasive articles.

In a sixth embodiment, the present disclosure provides a plurality ofchopped loose abrasive bodies according to any of the first to thirdembodiments, wherein at least some of the chopped loose abrasive bodiescomprise chopped unitized or convolute abrasive articles.

In a seventh embodiment, the present disclosure provides a plurality ofchopped loose abrasive bodies according to any of the first to thirdembodiments, wherein, on a respective basis, at least some of thesubstrates comprise resilient foam.

In an eighth embodiment, the present disclosure provides a plurality ofchopped loose abrasive bodies according to any of the first to thirdembodiments, wherein at least some of the substrates respectivelycomprise metal foil.

In a ninth embodiment, the present disclosure provides a plurality ofchopped loose abrasive bodies according to any of the first to eighthembodiments, wherein at least some of the abrasive particles comprisecrushed abrasive particles.

In a tenth embodiment, the present disclosure provides a plurality ofchopped loose abrasive bodies according to any of the first to ninthembodiments, wherein at least some of the abrasive particles compriseshaped abrasive particles.

In an eleventh embodiment, the present disclosure provides a pluralityof chopped loose abrasive bodies according to any of the first to tenthembodiments, wherein, on a respective basis, the abrasive particles aresecured to the substrate by a binder material.

In a twelfth embodiment, the present disclosure provides a plurality ofchopped loose abrasive bodies according to the eleventh embodiment,wherein the binder material comprises crosslinked organic bindermaterial.

In a thirteenth embodiment, the present disclosure provides a method ofabrading a surface of a workpiece, the method comprising:

providing a vessel containing:

-   -   loose abrasive bodies, wherein at least most of the loose        abrasive bodies have a maximum dimension of 0.25 to 3        centimeters, and wherein, on a respective basis, each loose        abrasive body comprises abrasive particles secured to an organic        substrate by a binder material; and    -   the workpiece; and

agitating the vessel with sufficient energy such that at least some ofthe loose abrasive bodies contact and abrade at least a portion of thesurface of the workpiece.

In a fourteenth embodiment, the present disclosure provides a methodaccording to the thirteenth embodiment, wherein the vessel has a maximumretaining capacity, and wherein the plurality of loose abrasive bodieshas a total volume that is at least 25 percent of the maximum retainingcapacity of the vessel.

In a fifteenth embodiment, the present disclosure provides a methodaccording to the fourteenth embodiment, wherein the plurality of looseabrasive bodies has a total volume that is at least 50 percent of themaximum retaining capacity of the vessel.

In a sixteenth embodiment, the present disclosure provides a methodaccording to any of the thirteenth to fifteenth embodiments, wherein thevessel is agitated by linear displacement.

In a seventeenth embodiment, the present disclosure provides a methodaccording to any of the thirteenth to sixteenth embodiments, wherein themethod is continuous.

In an eighteenth embodiment, the present disclosure provides a methodaccording to any of the thirteenth to seventeenth embodiments, whereinthe workpiece comprises metal.

In a nineteenth embodiment, the present disclosure provides a methodaccording to any of the thirteenth to eighteenth embodiments, whereinthe workpiece comprises plastic.

In a twentieth embodiment, the present disclosure provides a methodaccording to any of the thirteenth to nineteenth embodiments, whereinthe loose abrasive bodies comprise the plurality of chopped looseabrasive bodies of any of the first to twelfth embodiments.

Objects and advantages of this disclosure are further illustrated by thefollowing non-limiting examples, but the particular materials andamounts thereof recited in these examples, as well as other conditionsand details, should not be construed to unduly limit this disclosure.

EXAMPLES

Unless otherwise noted, all parts, percentages, ratios, etc. in theExamples and the rest of the specification are by weight.

The system used for all examples described below was a LabRAM ResonantAcoustic mixer from Resodyn Corporation, Butte, Mont. The machine, whichwas equipped with a sealed mixing vessel, was run at 100% intensity inthe auto frequency mode. Roughness measurements: R_(a), were measuredusing a MarSurf PS 10 stylus profilometer and S_(a) roughnessmeasurements were recorded using a MikroCAD surface metrology system.

Example 1

This example demonstrates abrading aluminum alloy with cloth-backedelectrocoated abrasive bodies.

The workpiece was a machined aluminum alloy (Grade BS EN 755 6082-T6) 16mm×3 mm×50 mm cuboid. The workpiece had an initial surface roughnessR_(a) of 4.3 microns. The workpiece was placed in a polypropylenecontainer with 55 mm internal height and 80 mm internal diameter. 53 gof 3M 947A 120+ cloth-backed electrocoated abrasive (chopped into 1 cm×1cm squares) was placed in the container along with the workpiece, andthe was container sealed with a lid. The LabRAM was run at 100%intensity in the auto frequency mode for 15 mins. The roughness R_(a) ofthe workpiece after 15 mins of processing was 2.1 microns. The mass lossof the workpiece during processing was 0.05 g (0.8% of the total initialmass).

Example 2

This example demonstrates abrading additively manufactured tool steelwith a microreplicated cloth-backed abrasive bodies.

The workpiece was an additively manufactured tool steel tube of 20 mmdiameter with 2 mm walls printed by DMLS. The initial roughness of theoutside of the tube was an R_(a) of 6.8 microns and 12.0 microns on theinside of the tube. The workpiece was placed in a polypropylenecontainer with 55 mm internal height and 80 mm internal diameter. 50 gof 3M 307EA A100 Trizact belt (chopped into 1.27 cm×1 cm rectangles) wasplaced in the container along with the workpiece, and the container wassealed with a lid. The LabRAM was run at 100% intensity in the autofrequency mode for 15 mins. After 15 mins, the roughness R_(a) of theworkpiece on outside surface of the tube was 3.0 microns, and on theinside surface the tube was 6.8 microns. The mass loss of the workpiecewas 0.17 g (1% of the total initial mass).

Example 3

This example demonstrates abrading aluminum alloy with foam backedelectrocoated abrasive bodies.

The workpiece was a machined aluminum alloy (Grade BS EN 755 6082-T6) 16mm×3 mm×50 mm cuboid. The workpiece had an initial surface roughnessR_(a) of 4.5 microns. The workpiece was placed in a polypropylenecontainer with 55 mm internal height and 80 mm internal diameter. 20 gof 3M P1000 Hookit Flexible Abrasive Foam Disc (foam-backedelectrocoated abrasive chopped into 1.5 cm×1.5 cm squares) was placed inthe container along with the workpiece. The container was sealed withits lid. The LabRAM was run at 100% intensity in the auto frequency modefor 15 mins. The roughness R_(a) of the workpiece after 15 mins ofprocessing was 2.5 microns. The mass loss of the workpiece duringprocessing was 0.02 g (0.3% of the total initial mass).

Example 4

This example demonstrates abrading additively manufactured tool steelwith double-sided foam-backed coated abrasive bodies.

The workpiece was an additively manufactured tool steel tube of 20 mmdiameter with 2 mm walls printed by DMLS. The initial roughness of theoutside of the tube was an R_(a) of 12.2 microns and 12.8 microns on theinside of the tube. The workpiece was placed in a polypropylenecontainer with 55 mm internal height and 80 mm internal diameter. 3M737U 400+ paper-backed coated abrasive was laminated to both sides ofsheet of soft foam (0.5 cm thick), and this construction was choppedinto 1 cm×1 cm squares. 18 g of the double-sided foam-backed abrasivebodies was placed in the container along with the workpiece, and thecontainer was sealed with a lid. The LabRAM was run at 100% intensity inthe auto frequency mode for 15 mins. After 15 mins. the roughness R_(a)of the workpiece on outside surface of the tube was 8.7 microns and onthe inside surface the tube was 5.2 microns. The mass loss of theworkpiece was 0.21 g (1.3% of the total initial mass).

Example 5

This example demonstrates abrading additively manufactured tool steelwith unitized wheel abrasive bodies.

The workpiece was an additively manufactured tool steel tube of 20 mmdiameter with 2 mm walls printed by DMLS. The initial roughness of theoutside of the tube was an R_(a) of 7.4 microns. The workpiece wasplaced in a polypropylene cylindrical container with 55 mm internalheight and 80 mm internal diameter. 3M Scotch-Brite Debunr and FinishPRO 6C Med+ Unitized Wheel (0.125 inch thickness) was chopped into 0.5cm×0.5 cm squares. 30 g of the unitized abrasive bodies was placed inthe container along with the workpiece, and the container was sealedwith a lid. The LabRAM was run at 100% intensity in the auto frequencymode for 15 mins. After 15 mins, the roughness R_(a) of the workpiece onoutside surface of the tube was 2.6 microns. The mass loss of theworkpiece was 0.21 g (1.3% of the total initial mass).

Example 6

This example demonstrates abrading aluminum alloy with lofty nonwovenabrasive bodies.

The workpiece was a machined aluminum alloy (Grade BS EN 755 6082-T6) 16mm×3 mm×50 mm cuboid. The workpiece had an initial surface roughnessR_(a) of 4.1 microns. The workpiece was placed in a polypropylenecylindrical container with 55 mm internal height and 80 mm internaldiameter. 30 g of 3M 7446 S-CRS Scotch-Brite (lofty nonwoven abrasivehandpad chopped into 1 cm×1 cm squares) was placed in the containeralong with the sealed. The container was sealed with a lid. The LabRAMwas run at 100% intensity in the auto frequency mode for 15 mins. Theroughness R_(a) of the workpiece after 15 mins of processing was 2.2microns. The mass loss of the workpiece during this time period ofprocessing was 0.02 g (0.3% of the total initial mass).

Example 7

This example demonstrates abrading aluminum alloy with paper-backedelectrocoated abrasive bodies.

The workpiece was a machined aluminum alloy (Grade BS EN 755 6082-T6) 16mm×3 mm×50 mm cuboid. The workpiece had an initial surface roughnessR_(a) of 4.2 microns. The workpiece was placed in a polypropylenecylindrical container with 55 mm internal height and 80 mm internaldiameter. 29 g of 3M P500 334U (paper-backed coated abrasive laminatedto brushed nylon, chopped into 1 cm×1 cm squares) was placed in thecontainer along with the workpiece and the container was sealed with alid. The LabRAM was run at 100% intensity in the auto frequency mode for15 mins. The roughness R_(a) of the workpiece after 15 mins ofprocessing was 2.8 microns. The mass loss of the workpiece duringprocessing was 0.04 g (0.6% of the total initial mass).

Example 8

This example demonstrates abrading additively manufactured tool steelwith paper-backed electrocoated abrasive bodies (waste pips).

The workpiece was an additively manufactured tool steel tube of 20 mmdiameter with 2 mm walls printed by DMLS. The initial roughness of theoutside of the tube was an R_(a) of 11.8 microns. The initial roughnessof the inside of the tube was an R_(a) of 12.4 microns. The workpiecewas placed in a polypropylene cylindrical container with 55 mm internalheight and 80 mm internal diameter. The abrasive bodies were 3M 255P P80pips. 3M 255P is a paper-backed coated abrasive laminated to brushednylon. Pips are circular pieces of coated abrasive removed to createdust extraction holes in a coated abrasive disc (in this case withdiameters 18 mm. 10 mm and 7 mm). 60 g of the pips was placed in thecontainer along with the workpiece, and the container was sealed with alid. The LabRAM was run at 100% intensity in the auto frequency mode for15 mins. After 15 mins, the roughness R_(a) of the workpiece on outsidesurface of the tube was 3.5 microns, and the R_(a) on the inside of thetube was 7.0 microns. The mass loss of the workpiece was 0.29 g (1.8% ofthe total initial mass).

Example 9

This example demonstrates abrading additively manufactured polymer withlofty nonwoven abrasive bodies.

The workpiece was an additively manufactured FormLabs Clear Resin(methacrylic acid esters with a photoinitiator) tube of 20 mm diameterwith 2 mm walls. The workpiece was printed by SLA (stereolithography)(initial roughness S_(a)=24 microns). The workpiece was placed in apolypropylene cylindrical container with 200 ml volume and 60 mminternal diameter. 25 g of 3M 7447 A-VFN Scotch-Brite (lofty nonwovenabrasive handpad chopped into 1 cm×2 cm squares) was placed in thecontainer along with the workpiece, and the container was sealed. TheLabRAM was run at 100% intensity in the auto frequency mode for 20 mins.After 20 mins, the roughness S_(a) of the workpiece on the surface ofthe tube was 2.7 microns (89% improvement). The mass loss of theworkpiece was 6% of the total initial mass.

Example 10

This example demonstrates the comparison between abrading aluminum alloywith coated abrasive bodies and loose abrasive grains.

The workpiece was a machined aluminum alloy (Grade BS EN 755 6082-T6) 16mm×3 mm×50 mm cuboid. The workpiece had an initial surface roughnessR_(a) of 4-4.5 microns. The workpiece was placed in a polypropylenecylindrical container with 55 mm internal height and 80 mm internaldiameter along with the abrasive media, and the container was sealedwith a lid. The abrasive media either comprised 60 g of 3M P80 255P pips(coated abrasive bodies), or 24 g, 60 g or 100 g of P80 semi-friablefused aluminum oxide BRFPL loose abrasive grain (Imerys). The reason forselecting these masses of loose abrasive grain are detailed in Table 1.The LabRAM was run at 100% intensity in the auto frequency mode for 5mins. The results for mass loss and surface finish improvement are shownin Table 1. The mass loss and surface finish improvements from thecoated abrasive bodies were significantly greater than from any mass ofthe loose abrasive grain.

TABLE 1 SURFACE FINISH IMPROVEMENT MASS OF MASS LOSS OF SUBSTRATE MEDIAIN FROM SURFACE, ABRASIVE DESCRIPTION OF ABRASIVE CONTAINER, SUBSTRATE,ROUGHNESS R_(a), MEDIA MEDIA g g microns NOTES 3M P80 Pips (7, 10 and 18mm diameter discs) of 60 0.052 27% Example of a coated 255P pips 3M P80255P coated abrasive (full abrasive body construction with brushed nylonattachment system and stearate coating) P80 BFRPL P80 grade aluminumoxide loose 24 0.024* −7% Approximate mass of abrasive grain abrasivegrain on 60 g of the coated abrasive P80 BFRPL P80 grade aluminum oxideloose 60 0.011  5% Same mass of abrasive abrasive grain grain as mass ofcoated abrasive P80 BFRPL P80 grade aluminum oxide loose 100 0.004 −1%Approximately same abrasive grain volume of abrasive grain as solidvolume of coated abrasive *Major mass loss from collisions of workpiecewith container.

All cited references, patents, and patent applications in thisapplication are incorporated by reference in a consistent manner. In theevent of inconsistencies or contradictions between portions of theincorporated references and this application, the information in thisapplication shall control. The preceding description, given in order toenable one of ordinary skill in the art to practice the claimeddisclosure, is not to be construed as limiting the scope of thedisclosure, which is defined by the claims and all equivalents thereto.

1-20. (canceled)
 21. A plurality of chopped loose abrasive bodies,wherein, on a respective basis, the chopped loose abrasive bodies eachcomprise abrasive particles secured to a substrate and have a maximumdimension of 0.25 to 1.5 centimeters, and wherein, on a respectivebasis, the abrasive particles are secured to the substrate by a bindermaterial.
 22. The plurality of chopped loose abrasive bodies of claim21, wherein the plurality of chopped loose abrasive bodies has apredetermined size distribution.
 23. The plurality of chopped looseabrasive bodies of claim 22, wherein the predetermined size distributionhas at least two modes.
 24. The plurality of chopped loose abrasivebodies of claim 21, wherein at least some of the chopped loose abrasivebodies comprise chopped coated abrasive articles.
 25. The plurality ofchopped loose abrasive bodies of claim 21, wherein at least some of thechopped loose abrasive bodies comprise chopped lofty open nonwovenabrasive articles.
 26. The plurality of chopped loose abrasive bodies ofclaim 21, wherein at least some of the chopped loose abrasive bodiescomprise chopped unitized or convolute abrasive articles.
 27. Theplurality of chopped loose abrasive bodies of claim 21, wherein, on arespective basis, at least some of the substrates comprise resilientfoam.
 28. The plurality of chopped loose abrasive bodies of claim 21,wherein at least some of the substrates respectively comprise metalfoil.
 29. The plurality of chopped loose abrasive bodies of claim 21,wherein at least some of the abrasive particles comprise crushedabrasive particles.
 30. The plurality of chopped loose abrasive bodiesof claim 21, wherein at least some of the abrasive particles compriseshaped abrasive particles.
 31. The plurality of chopped loose abrasivebodies of claim 21, wherein the binder material comprises crosslinkedorganic binder material.
 32. A method of abrading a surface of aworkpiece, the method comprising: providing a vessel containing: looseabrasive bodies, wherein at least most of the loose abrasive bodies havea maximum dimension of 0.25 to 3 centimeters, and wherein, on arespective basis, each loose abrasive body comprises abrasive particlessecured to an organic substrate by a binder material; and the workpiece;and agitating the vessel with sufficient energy such that at least someof the loose abrasive bodies contact and abrade at least a portion ofthe surface of the workpiece.
 33. The method of claim 32, wherein thevessel has a maximum retaining capacity, and wherein the plurality ofloose abrasive bodies has a total volume that is at least 25 percent ofthe maximum retaining capacity of the vessel.
 34. The method of claim33, wherein the plurality of loose abrasive bodies has a total volumethat is at least 50 percent of the maximum retaining capacity of thevessel.
 35. The method of claim 32, wherein the vessel is agitated bylinear displacement.
 36. The method of claim 32, wherein the method iscontinuous.
 37. The method of claim 32, wherein the workpiece comprisesmetal.
 38. The method of claim 32, wherein the workpiece comprisesplastic.
 39. The method of claim 32, wherein the loose abrasive bodiescomprise the plurality of chopped loose abrasive bodies of claim 21.